Anyone willing to look at my RX-7 with me? I really need a second set of eyes to help me figure out my hot start problems.

-If I park the car and it sits even for a few hours or so, the car will just sputter. The only way to get it to start it to pull the main fuse under the dash that goes to fuel pump, ecu, etc. I basically just have to pull it while I'm cranking and immediately put it back in and the car will start right up.

-Car will not idle smooth when stopped at a light, etc. Sometimes if I let the idle be for a few minutes it will smooth out.

What really frustrates me is that is the only problems. The car revs great, pulls great, etc. Also the car does start fine if it sits over night.

Okay, one thing I noticed this morning when I had to hot start the car. If the car is idling fine (750rpm) when I shut the car off, it will start perfectly the next time. If the car is idling sporadically (up and down, 500-1200 rpm) when I shut it down, it will not start easily.

That is odd, do you have any way to monitor Vacuum during the sporadic idle and compare to regular idle? Wondering if its the IACV opening and closing or CAS dropping signal to keep the fuel coming.
I also have some noid lights you can use, I'm sure someone around here has a spare vac/boost gauge also.

I have a set of noid lights as well, and I think I have a spare boost gauge in the shed.

How do you use noid lights if you can run the car with it plugged in? My car only has two injectors and they are under the upper intake.

I don't have a vacuum gauge.

Another thing that the car has always had a problem with is building pressure in the fuel tank. It gets worse in the summer.

RX-7 Chris wrote:How do you use noid lights if you can run the car with it plugged in? My car only has two injectors and they are under the upper intake.

I don't have a vacuum gauge.

Another thing that the car has always had a problem with is building pressure in the fuel tank. It gets worse in the summer.

I don't know, that's why I've never used them. HAHA.

Actually I think they're more to check if the injector is firing during cranking. I can't think of how you'd make them work while it's running, unless maybe you rigged a couple wires coming out the back of the injector connector.

Real engines (V8) will idle along just fine with an injector unplugged. But I can see how they are not a convenient tool when your injector plugs are not easily accessible. But like Speedjunk said you can make sure you are getting injector prime pulse and firing pulse while cranking.

Dwduc wrote:Real engines (V8)

I think you meant "Real engines (Chevy V8s)"... that is, of course, if you're referring to the V8s that produce real power

Dwduc wrote:Real engines (V8) will idle along just fine with an injector unplugged. But I can see how they are not a convenient tool when your injector plugs are not easily accessible. But like Speedjunk said you can make sure you are getting injector prime pulse and firing pulse while cranking.

I can pull the intake in about 15 minutes (done it way too many times) if you really think it is worth checking the prime pulse.

my concern is weather or not it is pulsing at starter crank speed, maybe when hot the CAS isn't getting a strong enough pulse to trigger the ecu to fire the injector.

This book explains Bosch L-jesction: http://foxed.ca/rx7manual/manuals/BOSCH%20L-Jetronic%20Injection%20Manual.pdf

Here is the section of the FSM explaining the system: http://foxed.ca/rx7manual/manuals/1985_RX7_FSM/85RX7(4B)Fuel%2526emissions_13B.pdf

I went to start the car this morning and it was flooded after sitting since Friday afternoon. I know my problem isn't the injectors because they were just done. I pulled the plugs and they were completely drenched in gas.

I'm really starting to wonder if maybe it is either the fuel pressure regulator or the ecu.

Wouldn't the FPR just hold fuel pressure to the rails? It can't make fuel dump into the engine can it? Maybe the ECU is opening the injectors after shutdown?

I miss my carburetors, I could actually find out what is wrong with it.

You're probably right Eric. I do have an extra ECU somewhere, maybe I should just swap it out.

My dad has the test gauges that I'm going to borrow from him and see if maybe I'm having problems there.